抽凝机组热电联产系统中扩大热电负荷比的灵活性研究

Enlargement of heat-electricity ratio for flexibility operation in a large-scale extraction condensing turbine system

为提高大型燃煤热电联产系统灵活供热能力以消纳间歇性可再生能源,本文以350 MW中间抽汽供热的燃煤凝汽机组为研究对象,利用Ebsilon软件构建了凝汽机组仿真模型,分别从热电负荷调节范围以及能耗特性等方面评价了中间抽汽、电锅炉与抽汽联合、电热泵、电热泵与抽汽联合、吸收式热泵以及切除低压缸等6种供热方式下大型燃煤热电联产系统的灵活性。结果表明:电热泵供热、电热泵与抽汽联合供热、吸收式热泵供热和切除低压缸供热分别将最大供热功率从中间抽汽供热的336 MW增加至631、563、453、545 MW,最大热电比从1.39增加至7.97、6.47、1.87和2.92;最大供热功率的标准煤耗从185 g/(kW·h)降低至137、147、152、140 g/(kW·h)。案例研究表明,在消纳高比例可再生能源背景下,电热泵供热方式能够有效降低系统的标准煤耗。

To improve the flexible heating capacity of large-scale coal-fired heat and power generation system for absorbing the intermittent renewable energy,a 350 MW coal-fired condensing unit with medium-pressure cylinder extraction steam for heating was selected as the research object in this paper,and then the flexibility of large-scale coal-fired CHP system was studied.Firstly,the simulation model of this condensing unit was built through the Ebsilon software.Next,six heating modes such as middle extraction steam,electric boiler coupling with extraction steam,electric heat pump,electric heat pump coupling with extraction steam,absorption heat pump as well as cutting out low-pressure cylinder,were evaluated respectively from the aspects of thermoelectric load adjustable range and energy consumption characteristics.The results show that,compared with middle extraction steam heating,the electric heat pump heating,electric heat pump coupling with extraction steam heating,absorption heat pump heating and cutting out low-pressure cylinder heating increase the maximum heating power from 336 MW to 631 MW,563 MW,453 MW and 545 MW,respectively.The maximum heat-electricity ratio increases from 1.39 to 7.97,6.47,1.87 and 2.92,and the average standard coal consumption rate in the maximum heating power heating mode reduces from 185 g/(kW·h)to 137,147,152 and 140 g/(kW·h),respectively.The case study shows that the electric heat pump heating mode can effectively reduce the average standard coal consumption rate of the system under the background of absorbing higher-proportion renewable energy.